Thermosetting plastics, for instance polyester, urethan and is epoxy can be mixed in fluid state and are fed out by means of a spray-gun, which is equipped with a nozzle providing a defined spray image. In this way, the plastic can be applied, e.g. in a mold for casting plastic products.
Generally, solvent agents are needed as gelling agents in the plastic, to allow it to receive correct viscosity for spraying through the nozzle.
This known technique involves drawbacks, as one generally has to calculate with a certain amount of spillage, when plastic due to an uncontrollable spray image wrongly lands in the mold or next to it. This spillage results in consuming an unnecessary large amount of plastic and also solvent agents. For environmental reasons such spillage should be minimized. Furthermore, it becomes difficult to maintain an even and high production quality, if one does not have control over the amount of plastic fed out per unit area.
The amount of the spillage will not be reduced, if the spray-gun, when spraying according to prior art, is moved closer to the surface to be covered with the thermosetting plastic, as drops of thermosetting plastic hitting a surface with a great force, tend to break into smaller drops, which rebound back towards the spray-gun.